As my colleague Eric Garcia reported, Rep. Earl Blumenauer went on a Twitter rant against President Donald Trump Monday night. The Oregon Democrat used the hashtag #LiarinChief to call out the commander in chief for a string of statements that bent the bounds of truth.

The venue was much different, but that’s the same sentiment Rep. Joe Wilson, R-S.C., rightly took a beating for, for expressing during an address by President Barack Obama to a joint session of Congress in 2009. Wilson’s a kind man who will nonetheless go down as the guy who yelled, “You lie!” at a sitting president in the House chamber. Appropriately, the House approved a resolution condemning Wilson’s behavior. Blumenauer voted in favor.

Now, though, Blumenauer’s all good with calling a president a liar — as long as it’s done on Twitter and even if Blumenauer lives in a glass house on one of his key complaints. He pointed out that Trump attributed a rift with the intel community to the media and then wrote “‪@POTUS has criticized the intelligence community time & time again, most recently w/ tweet.”

It’s kind of hard to take this from Blumenauer, who himself has been a harsh and consistent critic of the intelligence community.

“It has now grown so large and so secretive that we have no idea how much it costs or how many people it employs,” he said on the floor of the House just a few years ago during consideration of an annual intelligence authorization bill. Like Vermont Sen. Bernie Sanders, he’s long advocated slashing the nation’s intelligence budget.

In short, he’s the wrong guy to make arguments about who’s at war with the intelligence community and why. On the surface, he’s right that Trump lies, and it’s certainly his right to speak — or, God help us, tweet — his mind.

Some dignity, please …

But there’s a more important consideration here: It’s just not productive for most elected officials to engage in petty name-calling. That’s particularly true when it comes to matters so small as the size of the crowd at Trump’s inauguration. If Trump wants to diminish the importance of his moment and his office by making it about quantity rather than quality, a smart Democrat would happily step aside and let the president fall into that trap.

More broadly, Democrats are struggling with the question of whether they should defend norms of civility in the face of the election of a president who focused so much of his campaign trying to break them down.

Maybe, as Blumenauer is doing, they should act with childish impetuousness and fight as dirty as they can to delegitimize Trump. After all, that’s what Republicans, including Trump, tried to do to President Obama. But to interpret Trump’s victory as a triumph of his despicable brand of mudslinging is to misread the American public.

Trump’s birtherism didn’t deny Obama legitimacy; it robbed Trump of legitimacy until he abandoned the line of attack late last year. He was so convinced that it was doing him damage that he backtracked, despite the risk of alienating some supporters, in the interest of winning the presidency. Trump won “despite” the inane, insulting and unhinged things he said on the campaign trail not because of them.

Bigger faults?

Democrats would do well to attack Trump on substance rather than style, for the most part. If and when he does things that are beneath the dignity of his office, they shouldn’t respond by sinking below his level. They should simply point out that Trump’s behavior is unpresidential. There’s no need for name-calling. More important, there’s no political advantage in it.

When a member of Congress calls the president a liar, it’s easy to conclude the lawmaker can’t win on the merits of an argument. Blumenauer should spend more time worrying about honing his substantive case against Trump’s worldview than coming up with hashtags. The media will call out Trump for things he says that aren’t true. Big-league. So will the Twitterverse. Elected officials should be above name-calling — even if Trump wasn’t, as a candidate or in his first few days as president.

And Trump suddenly has newfound incentive to be decorous — to show that he is more fit to be president than many of his own voters thought. His hypersensitive demands that the press treat him better won’t get him as far as behaving more like a traditional president will. He needs credibility as commander in chief, and he’ll either realize that or he will drive himself and his party into such a deep political hole that Democrats, if they don’t mess it up, will be primed to take control of Washington again by 2020.

That is, Democrats will be fine if they don’t follow Blumenauer’s lead.